LPG fueled internal combustion engine powered devices

ABSTRACT

A gas phase of LPG such as propane is used to power a small internal combustion engine driving or powering a preselected device such as a powered lawnmower, weed whacker, string trimmer, leaf blower or the like and the fuel system is provided with heating arrangements that insure the gas phase of the LPG is discharged from the LPG tank for all operating conditions of the device.

INCORPORATION BY REFERENCE

Applicants incorporate by reference the teaching and technology asdisclosed in pending application Ser. No. 11/702,381, filed Feb. 6, 2007

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to Liquified Petroleum Gas (LPG) fueled internalcombustion engine powered arrangements and, more particularly, to sucharrangements in which the internal combustion engine is powered by thegas phase of the LPG at all times and may be as utilized in lawnmowers,weed whackers, leaf blowers, string trimmers and the like

2. Description of the Prior Art

Utilization of LPG as a fuel for internal combustion engines has beenheretofore been known for use in large internal combustion enginepowered arrangements such as forklifts, trucks, buses and other sucharrangements and devices. As such, the tank capacity of the LPG is quitelarge: on the order of 5 gallons or larger and in which the LPG iswithdrawn from the LPG tank in liquid phase form and this requires thatthe LPG tanks be mounted in a particular orientation so that only liquidphase LPG is withdrawn therefrom during operation of the internalcombustion engine 12. Further, the LPG tank is, generally, mounted inregions remote from the engine or any normally occurring heat sourceduring operation and/or storage of the device.

During operation of such devices, the liquid phase LPG travels throughtransfer lines to either a vaporizer or a vaporizer/regulator structure.The vaporizer or vaporizer/regulator causes the liquid phase LPG to beconverted to the gas phase LPG. The latent heat of vaporization of theliquid phase LPG as it is converted to the gas phase LPG would cause thevaporizer or vaporizer/regulator to get extremely cold and in manyapplications would freeze the liquid phase LPG to a solid phase and thusstop the flow of LPG to the engine unless means are provided to heat thevaporizer or vaporizer/regulator. Various structural arrangements haveheretofore been utilized to supply heat to the vaporizer orvaporizer/regulator. In liquid cooled internal combustion engines thehot engine coolant was often routed to pas through or adjacent to thevaporizer or vaporizer/regulator in order to transfer heat thereto. Inair cooled internal combustion engines some or all of the hot exhaustproducts may be forced over the vaporizer or vaporizer/regulator by theengine cooling fan. In other prior art applications, the LPG transferlines may be placed in close proximity to the exhaust manifold or thevaporizer or vaporizer/regulator may be close coupled to the exhaustmanifold for receiving heat therefrom.

In yet other prior art devices, an electrically powered heater wasprovided at the vaporizer or vaporizer/regulator.

Thus, such prior art applications and devices utilizing the large tanksof LPG often required many complex structural arrangements andcomponents in order to insure that the liquid phase LPG was converted tothe gas phase LPG.

In many other applications, the use of a large, e.g., 5 gallon LPG tankand its attendant complexity is not needed or desired. For example, inmany smaller internal combustion engine powered devices, it is oftendesired to utilize a small LPG tank such as one containing one or twopounds of LPG. Such devices include, but are not limited to lawnmowers,leaf blowers, string trimmers, or the like. The one or two pond LPGtanks are readily available as such LPG tanks are widely utilized in thecamping industry to provide LPG for portable for stoves, lamps and thelike. However, in such applications, the LPG tank is oriented to providethat only the gas phase LPG exits the LPG tank and, therefore, thefreezing of the LPG would occur in the LPG tank rather than external theLPG tank. Depending on the rate of flow of the gas phase LPG from theLPG tank, the freezing of the LPG occurs in the LPG tank.

However, in many applications it is desired that the mounting of the LPGtank be such that no specific orientation of the LPG tank is requiredfor the internal combustion engine to operate on the gas phase of theLPG.

Accordingly, there has long been a need in an It is another object ofthe present invention provide an LPG fueled internal combustion engineapparatus utilizing propane as the LPG from a conventional one to twopound LPG propane tank for the supply of the LPG and which does notrequire a particular orientation of the LPG tank with respect to gravityfor satisfactory operation.

Additionally, many of the prior art LPG fueled internal combustionengine powered devices have utilized butane as the LPG. Such devices arecommon in many foreign countries such as Japan and Korea. In the UnitedStates and in Europe, on the other hand, propane LPG tanks are quitereadily available. The physical properties of propane as compared tobutane makes the propane LPG tanks more attractive as a fuel for thesmall internal combustion engine applications. For example, for anequivalent amount of LPG, a butane fueled device would run for about onehalf hour while for a propane fueled device would run for about three tofour hours. Also, the butane LPG tanks that are readily available inJapan and Korea provide for only gas phase butane to be withdrawn fromthe bottle and are provided with an internal tube to insure that onlygas is withdraw and thus require a preferred orientation with respect togravity. Since liquid phase butane becomes a gas phase butane at about31 degrees F. which is only about 39 degrees F. different from theconventionally stated standard operating temperature of a nominal 70degrees F., there is little cooling effect due to the evaporation andfreezing in the LPG tank or in the system is not likely by utilizationin a small internal combustion engine. Liquid phase propane, on theother hand, becomes gas phase propane at about minus 44 degrees F. whichis about 114 degrees F. different from the conventionally statedstandard operating temperature of a nominal 70 degrees F. Therefore, thepropane would freeze to the solid phase in the LPG tank or elsewhere inthe delivery system long before the LPG tank is empty depending on theconsumption rate and the temperature. As contrasted to butane, thepropane requires structure to prevent freezing to the solid phase.

Therefore, it is an object of the present invention to provide an LPGfueled internal combustion engine apparatus utilizing propane as theLPG.

It is another object of the present invention to utilize a conventionalone to two pound LPG propane tank for the supply of the LPG.

It is another object of the present invention provide an LPG fueledinternal combustion engine apparatus utilizing propane as the LPG and inwhich the propane is provided from a conventional one to two pound LPGpropane tank for the supply of the LPG.

It is another object of the present invention provide an LPG fueledinternal combustion engine apparatus utilizing propane as the LPG from aconventional one to two pound LPG propane tank for the supply of the LPGand which does not require a particular orientation of the LPG tank withrespect to gravity for satisfactory operation.

It is another object of the present invention provide an LPG fueledinternal combustion engine apparatus utilizing propane as the LPG from aconventional one to two pound LPG propane tank for the supply of the LPGwhich does not require a particular orientation of the LPG tank withrespect to gravity for satisfactory operation and in which thepossibility of freezing of the liquid phase LPG to the solid phase LPGis substantially prevented in both the LPG tank and in the gas phasesupply system to the internal combustion engine.

It is yet another object of the present invention to provide an LPGfueled internal combustion engine apparatus utilizing propane as the LPGfrom a conventional one to two pound LPG propane tank for the supply ofthe LPG which does not require a particular orientation of the LPG tankwith respect to gravity for satisfactory operation and which insuresthat only gas phase LPG propane is withdrawn from the LPG tankregardless of the orientation thereof during operation.

SUMMARY OF THE INVENTION

The above and other objects of the present invention are achieved, in apreferred embodiment thereof as utilized in a LPG gas phase fueledinternal combustion engine lawnmower. This embodiment has an LPG tankcontaining propane which has both a liquid phase LPG and a gas phase LPGtherein mounted in a vertical orientation with respect to gravity sothat liquid phase LPG is at the discharge valve of the LPG tank for theconventional operation of the lawnmower on a relatively flat surfacethough operation will also satisfactorily occur for any otherorientation of the lawnmower such as, for example, on a sloping surfaceof lawn even though the gas phase LPG may be at the discharge valve.

The LPG tank is mounted by a mounting bracket on the internal combustionengine so as to be in both heat transfer relationship to a portion ofthe internal combustion engine from which the mounting bracket receivesheat as well as in vibration receiving relationship to the internalcombustion engine. The heat and vibration from the mounting bracket istransferred to the LPG tank and thus into the LPG in the LPG tank. Themounting bracket is also coupled to the discharge valve of the LPG tankso as to provide heating to the discharge valve.

The discharge valve of the LPG tanks utilized in the present inventionhas a spring biased poppet that is moved from a spring biased closedposition to an open position when coupled to a standard mounting plug.The standard mounting plug has a probe that unseats the poppet when themounting plug is attached to the discharge valve. As liquid phasepropane starts to flow from the LPG tank under the force produced by thegas pressure in the LPG tank, the small size of the orifice at thepoppet causes the liquid phase to vaporize into the gas phase. Since,depending on the flow rate of the liquid phase LPG through the poppetorifice, the latent heat of vaporization might cause the discharge valeto become so cold as to freeze the liquid phase LPG into the solid phaseLPG, heat is supplied to the mounting plug at the discharge valve so asto heat the discharge valve and thus prevent freezing of the LPG. Suchheating of the discharge valve may be provided by coupling a portion ofthe mounting bracket to the mounting plug.

The supply of gas phase LPG is passed from the mounting plug through ashutoff valve, through a pressure regulator and into the carburetor ofthe internal combustion engine. The carburetor is preferably a chokelesscarburetor of conventional design and may, if desired, be incorporatedas a single unit with the pressure regulator. The vacuum generated inthe carburetor by the operation of the internal combustion engine drawsthe gas phase LPG into the carburetor. At substantially zero vacuum, noliquid phase LPG is drawn into the carburetor. Gas phase LPG is drawninto the carburetor commensurate only with the vacuum thereby providingthat the gas phase LPG flow rate is at the rate demanded by the internalcombustion engine.

Thus, according to the principles of the present invention regardless ofwhether the liquid phase of the LPG or the gas phase of the LPG is atthe discharge port, satisfactory operation of the apparatus is insured.

In another embodiment of the present invention achieving the objects asstated above, the LPG tank may be mounted on an LPG fueled internalcombustion engine driven leaf blower or a string trimmer. As such, inoperation the leaf blower or string trimmer and, consequently, the LPGtank, may be in any orientation with respect to gravity. For thetechnological advances as described above, satisfactory operation isachieved by having only gas phase propane LPG flow from the LPG tankinto fuel supply system to the internal combustion engine.

BRIEF DESCRIPTION OF THE DRAWING

The above and other embodiments of the present invention my be morefully understood from the following detailed description taken togetherwith the accompanying drawing wherein similar reference characters referto similar elements throughout and in which:

FIG. 1 is an exploded view of a preferred embodiment of the presentinvention as utilized in an LPG fueled internal combustion enginepowered lawn mower;

FIG. 2 is a sectional view showing the attachment of the LPG tank to theinternal combustion engine in the embodiment illustrated in FIG. 1;

FIG. 2A is a block diagram illustrating the flow path of the fuel supplysystem of the present invention;

FIG. 3 illustrates another embodiment of the present invention asutilized in a string trimmer, leaf blower or the like; and

FIG. 4 is an exploded view of the attachment of the LPG tank to theembodiment illustrated in FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawing, there is shown on FIGS. 1 and 2 anembodiment, generally designated 10, of an LPG fueled internalcombustion engine apparatus utilizing the gas phase of propane as theLPG from a conventional one to two pound LPG propane tank for the supplyof the gas phase LPG and which does not require a particular orientationof the LPG tank with respect to gravity for satisfactory operation. Inembodiment 10, an internal combustion engine 12 is incorporated on apowered lawnmower 14. An LPG tank 16 is provided in a verticalorientation mounting position with respect to both gravity as indictedby the arrow 11 and the lawnmower 14 in the most common orientation ofthe lawnmower 14 during use which is generally horizontal. The LPG tank16 contains a liquified petroleum gas 18 such as, preferably, propane,though the LPG propane may include a mixture of propane with smallamounts of additives such as butane, propylene or other desiredadditives The LPG 18 in the tank 16 does not fill the tank completely sothat there is both a liquid phase 20 and gas phase 22 of the LPG 18 inthe tank 16. According to the principles of the present invention, theLPG utilized to fuel the internal combustion engine 12 is provided fromthe liquid phase 20 of the LPG which is vaporized to the gas phase atthe discharge of the LPG tank and thus prior to introduction to theinternal combustion engine 12.

A tank support bracket 24 is utilized for supporting the LPG tank 16 onthe internal combustion engine 12. In the embodiment 10, the bracket 24is mounted on the cylinder head 26 by head bolts 28. The tank supportbracket 24 preferably incorporates a quick release, such as an overcenter clamp for coupling the LPG tank 16 to the tank support bracket24, though other types of coupling arrangements such as an elastic band,a snap on latch, or even a hook and loop band or the like may beutilized as desired for particular applications. The tank supportbracket 24 is fixed to the cylinder head 26 of the internal combustionengine 12 by, for example, cylinder head bolts 30.

The tank support bracket 24 is, in preferred embodiments of the presentinvention, closely coupled to a part of the internal combustion engine12 so that it receives both vibration and heat from the internalcombustion engine 12 during operation of the internal combustion engine12. The vibration transferred from the internal combustion engine 12 tothe tank support bracket 24 and thus to the LPG tank 16 and the LPG 18provides agitation to the LPG 18 so as to aid in keeping the LPG 18 fromfreezing as the temperature thereof drops during the withdrawal of theLPG 18 therefrom, as described below in greater detail. Further, suchagitation of the LPG 18 increases the surface area 34 of the LPG 18 inthe tank 16 thereby causing an increase in the gas phase 22 of the LPGin the tank 16.

As shown more clearly in FIG. 2, in the conventional one to two poundpropane LPG tanks utilized in the present invention is provided with adischarge valve 32. The discharge valve 32 has a spring biased poppet 34normally biased into the closed position by spring 36. The dischargevalve 32 is threaded into a mounting plug 38 having a probe 40 thatunseats the poppet 34 against the bias of the spring 36 to allow thestart of the flow of liquid phase LPG therethrough. However, the floworifice 42 around the poppet is so small that the liquid phase propane20 is vaporized into the gas phase propane 22 a at the discharge valve32 as it flows through the mounting plug 38. The probe 40 of themounting plug 38 has walls defining a gas flow passage 40′ therethrough.

A clamping nut 44 having walls 46 defining a gas storage volume 48therein is provided and the gas volume 48 is in gas flow communicationwith the gas flow passage 40′ and contains the gas phase propane 22 auntil gas phase propane is required by the internal combustion engine12. The clamping nut 44 threadingly engages the mounting plug 38 at 44 aand clamps a heating portion 24 a of the mounting bracket 24 between theclamping nut 44 and the mounting plug 38. The heating portion 24 a ofthe mounting bracket 24 heats the mounting plug 38, the discharge valve32 and the clamping nut 44 to prevent any freezing of the gas phasepropane flowing through the orifice 42 of the discharge valve. An “O”ring 50 may be provided between the clamping nut 44 and the mountingplug 38.

The gas phase propane 22 a flows through a connector assembly 52 asindicated by the arrow 54.

A tank heating portion 24 b of the mounting bracket 24 is in heat andvibration transfer relationship to the LPG tank 16 to heat and agitatethe liquid phase LPG therein.

FIG. 2A illustrates a block diagram the flow path of the fuel systemaccording to the principles of the present invention. As shown on FIG.2A, the gas phase propane 22 a flows from the storage volume 48 into agas phase transmitting tube 61, through a shutoff valve 60 and for theshutoff valve in the open position thereof, into a gas phasetransmitting tube 61, through a pressure regulator 62 and into achokeless carburetor 64 for transmission to the internal combustionengine 12 as indicated by the arrows 54 a, 54 b, and 54 c. The shutoffvalve 60, pressure regulator 62 and chokeless carburetor 64 may be ofany desired commercially available gas phase design suitable for thepurpose. When the shutoff valve 60 is opened, gas phase propane 22 afrom the storage volume 48 of the clamping nut 44 is allowed to flow tothe internal combustion engine 12 in the amount as demanded by thevacuum created by the internal combustion engine 12.

Referring now to FIGS. 3 and 4 there is illustrated another preferredembodiment generally designated 100 of an LPG fueled internal combustionengine apparatus utilizing gas phase propane as the LPG from aconventional one to two pound LPG propane tank for the supply of the gasphase LPG and which does not require a particular orientation of the LPGtank with respect to gravity for satisfactory operation. The embodiment100 is shown as incorporated in a weed whacker, string trimmer, leafblower or the like. The power units of such devices are often strappedonto the back of the user and in use the user may bend to variousdegrees so that the orientation of the LPG tank may vary duringoperation with respect to the direction of gravity.

As shown on FIGS. 3 and 4, many of the components described above inconnection with embodiment 10 may be utilized in embodiment 100. the LPGtank 16 is connected to the internal combustion engine 12 by themounting bracket 24′ which is generally similar to the mounting bracket24 of embodiment 10 described above. the mounting bracket 24′ isprovided with a retaining strap 28 for securing the LPG tank 16 to themounting bracket 24′. In embodiment 100 the mounting bracket 24′ iscoupled to the crankcase 70 of the internal combustion engine 12. Thecrankcase 70 is another portion of the internal combustion engine 12which is heated during operation and thus heat and vibration aretransferred from the crankcase 70 to the mounting bracket 24′ and thusto the LPG tank 16 by the portion 24 b′ and to the discharge valve 32 bythe portion 24 a′ to prevent conversion of the gas phase of the LPGflowing through the discharge valve 32 to the solid phase.

The mounting bracket 24′ is retained against or in close proximity tothe crankcase 70 to provide the heat transfer and vibration transferthereto by bolts 72 and 74. The gas phase propane from the LPG tank 16through the shutoff valve 60 to the pressure regulator 62 as indicatedby arrow 54 a, from the pressure regulator 62 to the carburetor 64 asindicated by the arrow 54 b. The gas phase propane is mixed with airflowing into the air filter 78 and to the cylinder of the internalcombustion engine 12.

In FIGS. 3 and 4, the cylinder 26′ of the internal combustion engine 12may be aligned vertically with respect to the direction of gravity 11and the LPG tank mounted horizontally or at right angles to the cylinder26′. This relationship between the cylinder 26′ and the LPG tank 16 ismaintained regardless of the orientation of the embodiment 100 withrespect to the direction of gravity 11 as the user (not shown) may bendor twist during use. Thus, it is possible for either liquid or gas phasepropane to be at the discharge valve 32. However, in accordance with theprinciples of the present invention, it makes no difference since thereis heat transfer and vibration transfer to the contents of the LPG tank16 as well as to the discharge valve 32. Therefore, regardless ofwhether the liquid phase LPG tends to freeze in the tank 16 or at thedischarge valve 32 the heat and vibration transferred is sufficient toprovide that there is gas phase propane flowing into the shutoff valve60.

If the liquid level of the liquid propane in the LPG tank 16 is belowthe discharge valve 32 gas phase propane will flow therefrom to theshutoff valve 60. If the liquid level of the liquid phase propane in theLPG tank 16 is above the discharge valve 32, it is converted to the gasphase propane as described above. No matter where the freezing of thepropane to the solid phase might occur, the heat transfer and vibrationtransfer prevents such freezing regardless of the flow rate of thepropane.

A recoil starter of conventional design as indicated at 80 may beincorporated on the internal combustion engine 12 in the embodiment 100and, if desired a similar recoil starter may be incorporated in theembodiment 10.

From the above it can be seen that there has been provided an improvedgas phase fueled internal combustion engine adapted to power varioustypes of devices. and in which only gas phase LPG flows from the LPGtank regardless of the orientation of the LPG tank with respect togravity and regardless of whether liquid phase propane or gas phasepropane is present at the discharge of the LPG tank. Such arrangementseliminate the need for costly and complex heating devices downstreamfrom the LPG tank to convert the liquid phase propane to the gas phasepropane before introduction thereof into the carburetor of the internalcombustion engine.

Although specific embodiments of the present invention have beendescribed above with reference to the various Figures of the drawing, itshould be understood that such embodiments are by way of example onlyand merely illustrative of but a small number of the many possiblespecific embodiments which can represent applications of the principlesof the present invention. Various changes and modifications obvious toone skilled in the art to which the present invention pertains aredeemed to be within the spirit, scope and contemplation of the presentinvention as further defined in the appended claims.

1. A mounting arrangement for mounting an LPG tank containing bothliquid phase and gas phase LPG therein on an internal combustion engineof the type adapted to be fueled by the gas phase of the LPG and inwhich the internal combustion engine powers a predetermined device andin which the LPG tank has a discharge valve of the type having a springbiased poppet biasing the poppet into the closed position thereof toprevent the release of either gas phase or liquid phase LPG from the LPGtank, comprising, in combination: a mounting plug coupled to thedischarge valve and said mounting plug having: a probe for engaging thepoppet of the discharge valve of the LPG tank to unseat the poppetagainst spring bias; whereby liquid phase LPG is converted to gas phaseLPG in passage by the poppet; and, walls defining a gas flow passage forreceiving the gas phase LPG from the discharge valve; a clamping nutcoupled to the mounting plug and having walls defining a gas phasestorage volume in gas flow communication with said gas flow passage ofsaid probe of mounting plug; a discharge valve heating portion of amounting bracket clamped between said mounting plug and said clampingnut for transmitting heat and vibration to the regions containing saiddischarge valve to prevent the gas phase LPG from freezing andconverting to the solid phase LPG; a gas phase transmitting tube coupledto said clamping nut for receiving said gas phase LPG from said gasphase storage volume of said clamping nut and allowing flow of said gas;phase LPG therethrough; a gas phase LPG pressure regulator for receivinggas phase LPG from said gas phase transmitting tube for regulating thepressure of said gas phase LPG to the value required for operation ofthe internal combustion engine; a chokeless carburetor for receiving gasphase LPG from said pressure regulator and mixing said gas phase LPGwith ambient air in preselected proportions, and transmitting saidmixture of gas phase LPG and ambient air to said internal combustionengine.
 2. The arrangement defined in claim 1 and further comprising: anLPG tank heating portion of said mounting bracket in heat transfer andvibration transfer relationship to said LPG tank for heating andvibrating the LPG in said LPG tank to prevent the freezing of the LPG insaid LPG tank.
 3. The arrangement defined in claim 2 wherein: saidcoupling of said mounting nut to said discharge valve is a threadingcoupling.
 4. The arrangement defined in claim 3 and further comprising:an “O” seal between said clamping nut, said discharge heating portion ofsaid mounting bracket and said discharge valve of said LPG tank.
 5. Thearrangement defined in claim 1 wherein: said mounting bracket is mountedin heat and vibration transfer relationship to a cylinder cylinder headof the internal combustion engine.
 6. The arrangement defined in claim 5wherein: said mounting bracket is bolted to said internal combustionengine.
 7. The arrangement defined in claim 1 wherein: said LPG tank ismounted vertically with respect to the direction of gravity to provideliquid phase LPG at said discharge valve of said LPG tank duringsubstantially the normal operation of the device powered by saidinternal combustion engine.
 8. The arrangement defined in claim 7wherein the device is a powered lawnmower.
 9. The arrangement defined inclaim 1 wherein: said LPG tank is mounted at right angles to thedirection of gravity for the device in an upright position wherebyeither liquid phase or gas phase LPG may be present at the dischargevalve of said LPG tank depending on the orientation of the device withrespect to the direction of gravity and the amount of LPG in the LPGtank.
 10. The arrangement defined in claim 9 wherein: said device isselected from the class consisting of string trimmers, leaf blowers andweed whackers.